Manually operated air pumps for the inflation of bicycle tires are known in the art. By "pump" is meant a device which causes fluid flow, and which usually compresses a gaseous fluid and delivers it under pressure to an enclosed space. By "air" is meant any gas, preferably ambient atmosphere. Typically, hand operated pumps are one stage pumps in which air is drawn into the pump and trapped when the user pulls a handle up and discharged when the handle is depressed. For example, U.S. Pat. No. 639,552, issued in 1899, discloses a pump having a handle. By depressing the handle, the trapped air is compressed and forced into the enclosed space. A one-way valve is often employed to prevent exit of the compressed air. Some new hand operated pumps are double action pumps which generate compression on both up and down strokes.
Serious cyclists carry hand-operated air pumps for inflation of bicycle tires. The pumps must be compact, portable, and light weight. Preferably such pumps can be attached to the frame of the bicycle or are small enough to store in a pack. Unfortunately, as will be shown, presently available pumps are cumbersome and difficult to utilize.
One variety of commercially available pump is the floor pump. An example of the floor pump is the BLACKBURN TP-2 TrackPump.TM.. The user of a floor pump takes the hose and attaches it to the bike, steps on the footpeg to provide stability, and pumps the handle, up and down. The footpeg allows the user to hold the pump in place during the up stroke. The problem with the floor pump is that it cannot be carried on a bicycle trip because it is heavy, bulky, and improperly shaped to attach to the bicycle frame or store in a pack. Thus the floor pump usually remains in the cyclist's garage and is not taken on bicycle trips.
Another commercially available pump is the tube pump. An example of the tube pump is the ZEFAL Mountain Plus.TM.. The tube pump is easy to attach to a bicycle frame, and the tubular shape is aerodynamic so as to reduce drag. While it can be carried on the bicycle, there are numerous drawbacks of the tube pump. The tube pump lacks a hose, therefore the tube pump nozzle must be held in place against the tire valve and cannot be rested on the ground for stability. Even if placed on the ground, the tube pump would lack a footpeg. In addition, instead of a handle that is perpendicular to the tube, the pump handle is a portion of the tube. In sum, due to the construction of the tube pump, first it is difficult to keep in place against the tire and second the pump wastes effort as the user must hold the pump in place with one arm against the force applied by the other arm to depress the handle.
The earliest air pumps are illustrated by U.S. Pat. Nos. 575,430; 639,552; 643,429; and 643,806. All of these pump designs suffer from one or more of the problems afflicting the ZEFAL and BLACKBURN pumps; either they are bulky and cannot be attached to the frame, or they can't be stabilized against the ground.
Another pump, as described in U.S. Pat. Nos. 4,712,592 and 4,842,290, stores the cylinder of the pump in the frame as part of the post for the seat. This pump is not useful because the seat is bulky and inconvenient to use as a handle for the pump. In addition, it is difficult and time consuming to disassemble the bike to use the pump.
Yet another type of air pump for bicycle tires, described in U.S. Pat. No. 5,180,283, utilizes a rotating flywheel and pull-strap. The disadvantages of this pump are a complicated pump structure, and the preference of cyclists for the traditional pump with a handle.
Still another type of pump, as described in U.S. Pat. Nos. 4,185,670 and 4,773,454, utilizes a tank of compressed air to provide the pressure to inflate the bicycle tire. The disadvantages of such a pump include the expense of additional compressed air cylinders, the space these cylinders require in a pack, and the possibility that the cyclist will run out or forget to pack the cylinders.
As can be seen from the preceding discussion, what is needed is an ordinary hand-operated bicycle tire pump which is light and easy to carry and attach to a bicycle frame, yet has the advantages of a floor pump which can anchored against the ground with a footpeg the handle is pulled and stabilized against the ground when the handle is pushed.